1. Field of the Invention
This invention relates to a catalyst for the conversion of aromatic hydrocarbon compounds, and more specifically relates to a catalyst for the conversion into toluene and aromatic hydrocarbon compounds having 8 carbon atoms, a more useful gasoline base, by reacting benzene with aromatic hydrocarbon compounds having 9 or more carbon atoms.
This invention further relates to a method of converting aromatic hydrocarbon compounds, and more specifically relates to a method of converting aromatic hydrocarbon compounds into toluene and aromatic hydrocarbon compounds having 8 carbon atoms, a more useful gasoline base, by reacting benzene with aromatic hydrocarbon compounds having 9 or more carbon atoms.
2. Background Art
Aromatic hydrocarbon compounds contained in a gasoline base generally have higher octane values, and are superior as a gasoline base because of their high calorific value. Among them, toluene and aromatic hydrocarbon compounds having 8 carbon atoms especially have higher octane values and drive-ability levels, and thus their contents are desirable to be increased. In particular, methods of directly converting benzene and aromatic hydrocarbon compounds having 9 or more carbon atoms in the gasoline fraction into toluene and aromatic hydrocarbon compounds having 8 carbon atoms are significantly meaningful.
Reactions of aromatic hydrocarbon compounds to convert aromatic hydrocarbon compounds having different carbon atoms include the transalkylation reaction and the disproportionation reaction. The transalkylation reaction allows a reactant to react with plural different aromatic hydrocarbon compounds, while the disproportionation reaction of aromatic hydrocarbon compounds is a reaction between the same aromatic hydrocarbon compounds with two molecules.
A well known process regarding these reactions is the manufacture of benzene and xylene utilizing the disproportionation reaction of toluene. Further, as an application of this reaction, there also exists a method of increasing xylene yields through inducing transalkylation by adding aromatic hydrocarbon compounds having 9 or more carbon atoms into the starting materials.
However, this process does not require benzene as a starting material, but requires toluene which itself is useful as a gasoline base. In addition, highly purified materials are used in this process because it is designed to synthesize chemical industrial starting materials, and thus no particular attention has been paid to gasoline fractions, etc. which are mixtures of other compounds, namely various kinds of hydrocarbon compounds including aliphatic hydrocarbon compounds.
The U.S. Pat. No. 5,347,061 discloses a method of directly converting benzene and aromatic hydrocarbon compounds having 9 or more carbon atoms in the gasoline fraction into toluene and aromatic hydrocarbon compounds having 8 carbon atoms. The disclosed method is a process of manufacturing toluene and aromatic hydrocarbon compounds having 8 carbon atoms by inducing transalkylation, alkylation and decomposition of the fractions of hydrocarbon compounds with 6 carbon atoms which is rich in benzene and obtained by distilling reformed gasoline and the fractions of mixture of a aromatic hydrocarbon compounds with 9 or more carbons and non-aromatic hydrocarbon compounds in the presence of acidic metalosilicate catalyst. As for the acidic metarosilicate catalysts, there is disclosed zeolite catalysts such as ZSM-5 as preferable compounds, but no detailed description with regard to diameters of micropores of the carrier or carrying a metal on a carrier has been made.
It is an object of the present invention to provide a catalyst having a high activity and selectivity with less deactivation and suitably used for converting compounds comprising benzene and aromatic hydrocarbon compounds having 9 or more carbon atoms into toluene and aromatic hydrocarbon compounds having 8 carbon atoms, which is a more useful gasoline base.
It is another object of the present invention to provide a method of converting compounds comprising benzene and aromatic hydrocarbon compounds having 9 or more carbon atoms into toluene and aromatic hydrocarbon compounds having 8 carbon atoms, a more useful gasoline base.
As a result of elaborate efforts by the inventors to develop a novel catalyst to be used for direct conversion into toluene and aromatic hydrocarbon compounds having 8 carbon atoms as a more useful gasoline base by allowing benzene to react with aromatic hydrocarbon compounds having 9 or more carbon atoms, they have successfully found that a catalyst having a specific metal carried on a carrier containing zeolites with a large maximum diameter of the micropores and a large ratio of SiO2 to Al2O3 has a high activity and a excellent selectivity with less deactivation when it is used with a material oil having a specific range of a boiling point.
According to one aspect of the present invention, there is provided a catalyst for converting benzene and aromatic hydrocarbon compounds having 9 or more carbon atoms contained in a material oil having a boiling point of 30xcx9c210xc2x0 C. into toluene and aromatic hydrocarbon compounds having 8 carbon atoms in the presence of hydrogen, said catalyst being obtained by allowing a carrier containing zeolites in which the maximum diameter among diameters of its micropores is 0.6xcx9c1 nm and the ratio of SiO2/Al2O3 is 50 or more to carry at least one kind of metal or its compounds, the metal being selected from Group VIII and Group VIA of the Periodic Table.
According to the second aspect of the present invention, there is provided a method of converting benzene and aromatic hydrocarbon compounds having 9 or more carbon atoms contained in a material oil having a boiling point of 30xcx9c210xc2x0 C. into toluene and aromatic hydrocarbon compounds having 8 carbon atoms in the presence of hydrogen and a catalyst obtained by allowing a carrier containing zeolites in which the maximum diameter among diameters of its micropores is 0.6xcx9c1 nm and the ratio of SiO2/Al2O3 is 50 or more to carry at least one kind of metal or its compounds, the metal being elected from Group VIII and Group VIA of the Periodic Table.
Hereinafter the present invention will be more particularly described along with the accompanying drawings.